This invention is related to face seal and seat structures for ball valves or spherical plug valves wherein the seat ring is constructed of separate pieces and resiliently urged toward the valve member. This invention is also related to springs for valve seat rings which urges or biases the seat ring toward the valve member from behind the seat ring in the seat pocket.
Prior art spherical plug valve seat rings are typically constructed of a single piece annular member and placed in the valve seat pocket. In another typical construction, the seat ring structure includes a resilient sealing element pressed into a one-piece seat ring. In these two-piece constructions, the mounting of the seal ring is difficult in that it must be pressed into a groove in the seat ring or it must be placed into a groove in the seat ring and then the seat ring deformed to grip or secure the seal ring. In the latter construction it is desirable because of the choice of seal ring shapes available. However, this construction is not desirable because from a manufacturing standpoint, it is difficult to consistently mass produce. In regard to the urging means for seat rings it is quite common in the art to use wave springs or a plurality of spaced helical springs behind a seat ring to urge it towards a valve member. In these constructions they function well until foreign matter becomes lodged in the seat pocket around the springs at which point the seat ring becomes essentially fixed in its position and does not operate as required.